Refixation strategies in four patients with macular disorders

Purpose: This study was undertaken to identify visual search strategies per formed during refixation tasks in four patients with central scotomas. Meth ods: Eye movements of tested patients were recorded while they alternately fixate a central spot and recognized letters successively projected in vari ous locations. Results: Five oculomotor behavior patterns could be identifi ed: (1) a 'foveation-defoveation' strategy, directing the anatomic fovea, t hen the PRL, close to the target image; (2) a 'direct refixation' strategy, orienting the preferred retinal locus (PRL) straight onto the target image ; (3) a 'staircase' strategy, bringing the PRL by means of short successive saccades progressively closer to the target image; (4) a 'withdrawal' stra tegy, in which the scotoma was directed far away from the target image and then the PRL was brought onto it; and (5) a 'no-movement' behavior, in whic h the subject attempted to decipher the letter from his initial gaze positi on. Conclusion: Findings suggest that the visuomotor behaviors in the four studied patients were related to a variety of factors, including the locati on of the target image relative to the scotoma, the spatial characteristics of the defect, and the duration of the disease.